Method for removing arsenic from copper smelting soot and comprehensive recovery of valuable metals

Abstract

Provided is a method for removing arsenic from copper smelting soot and comprehensive recovery of valuable metals. According to the method, a metal leaching synergist is prepared through thiol-ene click chemical reaction, which is capable of reacting more effectively with arsenic and metal impurities in the copper smelting soot due to its special chemical structure, thereby improving leaching efficiency; and the cage-like structure of the polysilsesquioxane provides excellent chemical stability, the removal rate of harmful substances in the copper smelting soot can be increased by using the synergist, environmental pollution is reduced, meanwhile, the recovery rate of metal resources is increased, and the requirements of green chemistry and sustainable development are met. The present disclosure realizes the centralized management of As and also realizes the step-by-step recovery of valuable metals such as Cu, Zn, Pb, Bi, and In.

What is claimed is: 
     
       1. A method for removing arsenic from copper smelting soot and comprehensive recovery of valuable metals, wherein the method comprises the following steps: performing pretreatment and subjecting oxidative acid leaching; specifically, washing the pretreated leaching residue with water and subsequently sending it for oxidative acid leaching; and the oxidative acid leaching adopts a two-stage countercurrent method, and the operation steps are as follows:
 A1 first-stage leaching: continuously introducing air during the leaching process, adding water and stirring, maintaining a liquid-to-solid ratio (3-4): 1 and a temperature of 70-80° C., adding 60-70 g/L sulfuric acid, and reacting for 2-4 h; subsequently extracting In from the leachate using tributyl phosphate; then extracting Cu from the raffinate; and finally preparing basic zinc carbonate from the raffinate; and 
 A2 second-stage leaching: continuously introducing air during the leaching process, adding water and stirring, maintaining a liquid-to-solid ratio of (3-4): 1 and a temperature of 70-80° C., adding 120-130 g/L sulfuric acid, 10-15 g/L sodium chloride, and 0.02-0.3 g/L metal leaching synergist, reacting for 2-4 h, returning the second-stage leachate to the first-stage leaching process, and recycling for reuse; subsequently, neutralizing and hydrolyzing the leachate to separate Bi; finally reducing and smelting the leaching residue to recover Pb; 
 the preparation method of the metal leaching synergist is as follows: 
 according to parts by weight, stirring 5-10 parts of 1,3,5-triazine-2,4,6 (1H,3H,5H)-trithione, trisodium salt, 0.07-0.2 part of 5,10,15,20-tetrakis(4-vinylphenyl) porphyrin, 0.6-2.5 parts of acrylo polysilsesquioxane cage mixture, 120-160 parts of toluene, and 0.5-2.5 parts of photoinitiator, reacting for 50-100 minutes under the irradiation of 365 nm ultraviolet light, and then removing the toluene via reduced pressure distillation after the reaction is finished, to obtain the metal leaching synergist. 
 
     
     
       2. The method for removing arsenic from copper smelting soot and comprehensive recovery of valuable metals according to  claim 1 , wherein the pretreatment operation steps are as follows:
 Step 1, alkali leaching: adding copper smelting soot into a stirring kettle, adding water and stirring, maintaining a liquid-to-solid ratio of (4-5): 1, continuously adding 40-50 g/L of sodium hydroxide and 30-40 g/L of sodium sulfide, heating to increase the temperature, soaking and filtering to obtain the leachate and leaching residue; 
 Step 2 sedimentation: adding 10-20 g/L of lime into the leachate from Step 1, precipitating and filtering, continuously adding 5-10 g/L of polyaluminum chloride into the filtrate for flocculation and sedimentation to obtain filtrate and filter residue; and the filter residue is arsenic residue; and 
 Step 3: the filtrate from Step 2 is returned to the stirring kettle of Step 1 and used as a circulating liquid; and the leaching residue from Step 1 is sent for oxidative acid leaching for further treatment. 
 
     
     
       3. The method for removing arsenic from copper smelting soot and comprehensive recovery of valuable metals according to  claim 2 , wherein the main components of the copper smelting soot include: 7.18% Cu, 23.05% Pb, 4.09% Bi, 10.91% Zn, 6.01% As, 1.56% Cd, 4.05% Fe, 1.18% Sn, 0.595% Sb, and 0.021% In. 
     
     
       4. The method for removing arsenic from copper smelting soot and comprehensive recovery of valuable metals according to  claim 2 , wherein the soaking temperature of Step 1 is 60-70° C., the leaching time is 60-120 min, and the stirring speed is 500-600 rpm. 
     
     
       5. The method for removing arsenic from copper smelting soot and comprehensive recovery of valuable metals according to  claim 1 , wherein the photoinitiator is one of 2,2-dimethoxy-2-phenylacetophenone, benzophenone, benzoin dimethyl ether and isopropyl thioxanthone.